Resident Penguin doesn't use bullet collision, actually. It uses two dummy objects on either side of the penguin to determine roughly which enemies are directly in front of it. Then it highlights one...

I 100%'d Melee. Took FOREVER to get that Final Challenge against Mewtwo, Ganondorf, and Giga Bowser, but I got it. Link's forward smash has a big enough hitbox to hit all three of them if you charge...